Client
CF Industries, Inc.
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Location
Lakeland, Florida
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Project Costs
Engineering: $58,000
Construction: $300,000
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Start Date
September 2006
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Completion Date
Engineering: May 2007
Construction: June 2007 

Scope

BCI was hired by CF Industries to develop and pilot-test a stream  restoration construction approach utilizing an innovative hydraulic carving method. This approach requires fewer design parameters than conventional methods, thereby simplifying design and reducing the potential for errors. It harnesses forces that normally take decades to form natural channels on their own and accelerates them to occur over a matter of weeks.

Following mechanical construction of the stream valley, a pump was utilized to provide the predetermined flow needed to hydraulically carve the reclaimed channel. The design was based on the theory (Dominant Discharge Theory) that a constant water flow through a  valley equal to the effective discharge would result in channel dimensions and patterns similar to those produced by much more variable, natural flow distribution.

The channel formed by “headcutting”, wherein formation starts at the downstream end and the stream “cuts” its way up the valley. Regular measurements of the channel cross sections taken during the hydraulic construction activity indicate that channel formation began immediately, with the largest changes in the lower 250 feet occurring within three days; channel development toward equilibrium progressed more slowly thereafter with the equilibrium dimensions reached in four weeks. Two water flow rates (3,000 gpm and 6,000 gpm) were applied before desired stream size was attained. Large Woody Debris (LWD), consisting of logs and felled trees, was placed throughout the channel to encourage channel complexity and ultimately provide habitat. As the channel developed, LWD was added and/or altered to direct and support desired morphologies.

The results of this project verify that phased discharge increments using the Dominant Discharge Theory can be utilized to achieve desired channel dimensions and habitat complexities (e.g. bends, pools, riffles, undercut banks, leaf packs). Recirculated water and LWD were successfully combined to induce bed and velocity complexities important to aquatic flora and fauna.

BCI tasking included:

• Project Management
• Original scientific assessment
• Design protocol development
• Stream restoration design plans
• Topographic measurements
• Habitat mapping
• Velocity monitoring
• Construction and surveying inspection and supervision
• Statistical summaries
• Final writing, editing and publishing of the summary reports